From: Rik van Riel <riel@xxxxxxxxxx> Subject: x86: ascii armor the x86_64 boot init stack canary Use the ascii-armor canary to prevent unterminated C string overflows from being able to successfully overwrite the canary, even if they somehow obtain the canary value. Inspired by execshield ascii-armor and Daniel Micay's linux-hardened tree. Link: http://lkml.kernel.org/r/20170524155751.424-4-riel@xxxxxxxxxx Signed-off-by: Rik van Riel <riel@xxxxxxxxxx> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Daniel Micay <danielmicay@xxxxxxxxx> Cc: "Theodore Ts'o" <tytso@xxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/include/asm/stackprotector.h | 1 + 1 file changed, 1 insertion(+) diff -puN arch/x86/include/asm/stackprotector.h~x86-ascii-armor-the-x86_64-boot-init-stack-canary arch/x86/include/asm/stackprotector.h --- a/arch/x86/include/asm/stackprotector.h~x86-ascii-armor-the-x86_64-boot-init-stack-canary +++ a/arch/x86/include/asm/stackprotector.h @@ -74,6 +74,7 @@ static __always_inline void boot_init_st get_random_bytes(&canary, sizeof(canary)); tsc = rdtsc(); canary += tsc + (tsc << 32UL); + canary &= CANARY_MASK; current->stack_canary = canary; #ifdef CONFIG_X86_64 _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
